Vacuum Tube Regeneration

[Electronic M]

I read regeneration and expected radio recievers using positive RF feedback for more signal gain, not tube rejuvenation.

Still interesting though. Some 20s tubes that I didn't want to pay to replace I've tried similar with, only it was full manual. I'd just increase heater a click or two till it showed gradual improvement, once it stopped I'd drop it to normal let it cool a moment and recheck.